Federal agencies will call to temporarily suspend the use of Johnson & Johnson coronavirus vaccines, after six recipients of the vaccine developed a blood clotting disorder.

Almost seven million Americans have received the Johnson & Johnson vaccine, which is administered in a single dose. Six recipients, all of them women between ages 18 and 48, developed an extremely rare clotting disorder, known as cerebral venous thrombosis.

The Food and Drug Administration and the Centers for Disease Control and Prevention will investigate a possible link between the Johnson & Johnson vaccine and the clotting disorder, the New York Times reported. The agencies will also debate whether to continue FDA emergency authorization for the vaccine.

European regulators discovered a similar issue with the AstraZeneca coronavirus vaccine. Out of 34 million people to receive the AstraZeneca vaccine, 222 developed blood clots due to low platelet counts as a rare side effect.

However, in that case regulators said that the AstraZeneca vaccine should continue to be administered because the benefits outweighed the very low risk of side effects.